Korea: An original investigation entitled "Changes in Alcohol Consumption and Risk of Dementia in a Nationwide Cohort in South Korea", published in JAMA Network Open, has concluded that consuming mild to moderate alcohol reduces dementia risk. In contrast, heavy consumption of alcohol increases dementia risk.
Alcohol consumption is a potentially modifiable risk factor for dementia. There needs to be more investigation on the impact of serial changes in alcohol consumption on the risk of dementia.

The question here is whether alcohol consumption is tied to the incidence of dementia.
The researchers did a cohort study on 3 933 382 adults aged 55 years (mean age) with a follow-up of 6.3 years in Korea and found that mild to moderate alcohol consumption decreased dementia risk than sustained nondrinking, while heavy drinkers increased the risk of dementia. They investigated pattern association for changes in alcohol consumption with all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VaD). These were the primary study outcomes measured by the team.
Further study details are summarised below:
The data was used from the Korean National Health Insurance Service database.
The category of consuming alcohol was none, mild, moderate and heavy, with the drinking of 0 g per day, <15 g per day), 15-29.9 g per day and ≥30 g per day.
The individuals were categorised as non-drinkers, quitters, reducers, sustainers, and increasers.
The cases recorded of all-cause dementia, Alzheimer's disease and vascular dementia are 100 282, 79 982 cases, and 11 085 cases, respectively.
Sustained mild and moderate drinking had aHR of 0.79 and 0.83 than sustained nondrinking and tied to decreased all-cause dementia risk.
Sustained heavy drinking with aHR of 1.08 increased the risk of all-cause dementia.
Reducing alcohol consumption (heavy to moderate) and initiating mild alcohol consumption with a respective adjusted hazard ratio of 0.92 and 0.93 decreased the risk of all-cause dementia than the sustained level of drinking.
Increasers and quitters had a higher risk than sustainers for all-cause dementia.
To conclude, the threshold of alcohol consumption for dementia risk reduction is low.
Further reading:
Changes in Alcohol Consumption and Risk of Dementia in a Nationwide Cohort in South Korea. JAMA Netw Open. doi:10.1001/jamanetworkopen.2022.54771